Photosensitive resin composition and applications thereof

ABSTRACT

A photosensitive resin composition includes: an alkali-soluble resin; an o-naphthoquinonediazidesulfonic acid ester; a silsesquioxane having at least two thiol groups in a molecule; and a solvent. The silsesquioxane is obtained by subjecting to condensation a silane material which includes a thiol-group-containing silane represented by R a Si(OR b ) 3 . R a  represents a C 1 -C 8  organic group that contains a thiol group and that is free from an aromatic group, or an organic group that contains a thiol group and an aromatic group. R b  independently represents hydrogen, a C 1 -C 6  alkyl group, a C 1 -C 6  acyl group, or a C 6 -C 15  aromatic group.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Patent Application No.101135627, filed on Sep. 27, 2012.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a photosensitive resin composition, moreparticularly to a photosensitive resin composition for forming aprotective film having a good cross-sectional shape and a low linearthermal expansion coefficient. This invention also relates to aprotective film formed from the photosensitive resin composition, and anelement containing the protective film.

2. Description of the Related Art

While manufacturing an optical device such as a liquid crystal displayor a solid state imaging device, processing procedures such as soakingin acid or alkaline solutions and sputtering, and heat generated duringthe processing procedures may cause damage to the optical device.Therefore, a protective film is usually needed for protecting theoptical device.

The protective film is not only required to have superior resistance tochemicals, water, and solvents so as to provide sufficient protectionagainst the aforementioned conditions, but also to have good adhesion toa substrate, high transparency and good thermal and light resistances soas to alleviate whitening or yellowing problems after being in use for along period of time.

JP 2001-354822 discloses a radiation-sensitive resin composition forforming a protective film. The radiation-sensitive resin compositionincludes: (A) a copolymer of an unsaturated carboxylic acid and/or anunsaturated carboxylic acid anhydride, an epoxy-containing unsaturatedcompound, a maleimide monomer, and other olefinic unsaturated compound;and (B) 1,2-quinonediazide compound, wherein the amount of the1,2-quinonediazide compound (B) ranges from 5 to 100 parts by weightbased on 100 parts by weight of the copolymer (A). Suchradiation-sensitive resin composition has good sensitivity and theprotective film formed therefrom has good thermal resistance and solventresistance. However, the protective film has relatively high linearthermal expansion coefficient and inferior cross-sectional shape,thereby adversely affecting accuracy of processes such as forming awiring electrode layer on the protective film.

Therefore, there is a need in the art to provide a protective film thathas a good cross-sectional shape and a low linear thermal expansioncoefficient.

SUMMARY OF THE INVENTION

Therefore, a first object of the present invention is to provide aphotosensitive resin composition for forming a protective film having agood cross-sectional shape and a low linear thermal expansioncoefficient.

A second object of the present invention is to provide a protective filmformed from the photosensitive resin composition.

A third object of the present invention is to provide an elementcontaining the protective film.

According to a first aspect of the present invention, a photosensitiveresin composition includes (A) an alkali-soluble resin, (B) ano-naphthoquinonediazidesulfonic acid ester, (C) a silsesquioxane havingat least two thiol groups in a molecule, and (D) a solvent. Thesilsesquioxane is obtained by subjecting to condensation a silanematerial which includes a thiol-group-containing silane represented byformula (I):

R^(a)Si(OR^(b))₃  (I),

wherein R^(a) represents a C₁-C₈ organic group that contains a thiolgroup and that is free from an aromatic group, or an organic group thatcontains a thiol group and an aromatic group, and R^(b) independentlyrepresents hydrogen, a C₁-C₆ alkyl group, a C₁-C₆ acyl group, or aC₆-C₁₅ aromatic group.

According to a second aspect of the present invention, there is provideda protective film formed from the photosensitive resin composition.

According to a third aspect of the present invention, there is providedan element including the protective film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used herein, the term “(meth)acrylic acid” means acrylic acid and/ormethacrylic acid. Likewise, the term “(meth)acryloyl” means acryloyland/or methacryloyl, and the term “(meth)acrylate” means acrylate and/ormethacrylate.

According to the present invention, the photosensitive resin compositionincludes (A) an alkali-soluble resin, (B) ano-naphthoquinonediazidesulfonic acid ester, (C) a silsesquioxane havingat least two thiol groups in a molecule, and (D) a solvent. Thesilsesquioxane is obtained by subjecting to condensation a silanematerial which includes a thiol-group-containing silane represented byformula (I):

R^(a)Si(OR^(b))₃  (I),

wherein R^(a) represents a C₁-C₈ organic group that contains a thiolgroup and that is free from an aromatic group, or an organic group thatcontains a thiol group and an aromatic group, and R^(b) independentlyrepresents hydrogen, a C₁-C₆ alkyl group, a C₁-C₆ acyl group, or aC₆-C₁₅ aromatic group.

[Alkali-Soluble Resin (A)]

The alkali-soluble resin (A) is a resin that is soluble in an alkalisolution, and the chemical structure of the alkali-soluble resin (A) isnot limited hereto according to the present invention.

Preferably, the alkali-soluble resin (A) is a carboxyl-containing resinor a phenol-novolac resin.

Preferably, the alkali-soluble resin (A) is obtained by subjecting amixture to copolymerization in the presence of a polymerizationinitiator. The mixture can include: (i) an unsaturated carboxylic acidcompound and/or an unsaturated carboxylic anhydride compound (a1) and afirst unsaturated compound having an epoxy group (a2); (ii) theunsaturated carboxylic acid compound and/or the unsaturated carboxylicanhydride compound (a1), the first unsaturated compound (a2), and asecond unsaturated compound (a3) that is different from the unsaturatedcarboxylic acid compound and/or the unsaturated carboxylic anhydridecompound (a1) and the first unsaturated compound (a2); or (iii) theunsaturated carboxylic acid compound and/or the unsaturated carboxylicanhydride compound (a1) and the second unsaturated compound (a3).

<Unsaturated Carboxylic Acid Compound and/or Unsaturated CarboxylicAnhydride Compound (a1)>

The unsaturated carboxylic acid compound and/or the unsaturatedcarboxylic anhydride compound (a1) may be used in an amount ranging from5 to 50 parts by weight, preferably from 8 to 45 parts by weight, andmore preferably from 10 to 40 parts by weight based on 100 parts byweight of the alkali-soluble resin (A) used in the photosensitive resincomposition of the present invention.

The unsaturated carboxylic acid compound and/or the unsaturatedcarboxylic anhydride compound (a1) may be referred to as a compoundhaving an unsaturated group and a carboxylic group or carboxylicanhydride group. Examples of the unsaturated carboxylic acid compoundand/or the unsaturated carboxylic anhydride compound (a1) may include,but are not limited to, an unsaturated monocarboxylic acid compound, anunsaturated dicarboxylic acid compound, an unsaturated carboxylicanhydride compound, a polycyclic unsaturated monocarboxylic acidcompound, a polycyclic unsaturated dicarboxylic acid compound, and apolycyclic unsaturated carboxylic anhydride compound.

Examples of the unsaturated monocarboxylic acid compound may include,but are not limited to, (meth)acrylic acid, crotonic acid,α-chloroacrylic acid, ethacrylic acid, cinnamic acid,2-(meth)acryloyloxyethyl succinate monoester, 2-(meth)acryloyloxyethylhexahydrophthalate, 2-(meth)acryloyloxyethyl phthalate, andomega-carboxypolycaprolactone polyol monoacrylate (commerciallyavailable from TOAGOSEI Co., Ltd, Product name: ARONIX M-5300).

Examples of the unsaturated dicarboxylic acid compound may include, butare not limited to, maleic acid, fumaric acid, methylfumaric acid,itaconic acid, and citraconic acid.

Examples of the unsaturated carboxylic anhydride compound may include,but are not limited to, anhydride compounds of the aforementionedexamples of the unsaturated dicarboxylic acid compound.

Examples of the polycyclic unsaturated monocarboxylic acid compound mayinclude, but are not limited to, 5-carboxy-bicyclo[2.2.1]hept-2-ene,5-carboxy-5-methyl-bicyclo[2.2.1]hept-2-ene,5-carboxy-5-ethyl-bicyclo[2.2.1]hept-2-ene,5-carboxy-6-methyl-bicyclo[2.2.1]hept-2-ene, and5-carboxy-6-ethyl-bicyclo[2.2.1]hept-2-ene.

A non-limiting example of the polycyclic unsaturated dicarboxylic acidcompound is 5,6-dicarboxy-bicyclo[2.2.1]hept-2-ene.

A non-limiting example of the polycyclic unsaturated dicarboxylicanhydride compound is an anhydride compound of the aforementionedexample of the polycyclic unsaturated dicarboxylic acid compound.

Preferably, the unsaturated carboxylic acid compound and/or theunsaturated carboxylic anhydride compound (a1) is selected from thegroup consisting of acrylic acid, methacrylic acid, maleic anhydride,2-methacryloyloxyethyl succinate monoester, 2-methacryloyloxyethylhexahydrophthalate, and combinations thereof.

<First Unsaturated Compound Having an Epoxy Group (a2)>

The first unsaturated compound having an epoxy group (a2) may be used inan amount ranging from 10 to 70 parts by weight, preferably from 20 to70 parts by weight, and more preferably from 25 to 65 parts by weightbased on 100 parts by weight of the alkali-soluble resin (A) used in thephotosensitive resin composition of the present invention.

Examples of the first unsaturated compound having an epoxy group (a2)may include, but are not limited to, epoxy-group-containing(meth)acrylates, epoxy-group-containing α-alkylacrylates, and glycidylethers.

Examples of the epoxy-group-containing (meth)acrylates may include, butare not limited to, glycidyl (meth)acrylate, 2-methylglycidyl(meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 6,7-epoxyheptyl(meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, and3,4-epoxycyclohexylmethyl (meth)acrylate.

Examples of the epoxy-group-containing α-alkylacrylates may include, butare not limited to, glycidyl α-ethylacrylate, glycidylα-n-propylacrylate, glycidyl α-n-butylacrylate, and 6,7-epoxyheptylα-ethylacrylate.

Examples of the glycidyl ethers may include, but are not limited to,o-vinylbenzylglycidyl ether, m-vinylbenzylglycidyl ether, andp-vinylbenzylglycidyl ether.

Preferably, the first unsaturated compound containing an epoxy group(a2) is selected from the group consisting of glycidyl methacrylate,3,4-epoxycyclohexylmethyl (meth)acrylate, 6,7-epoxyheptyl methacrylate,o-vinylbenzylglycidyl ether, m-vinylbenzylglycidyl ether, andp-vinylbenzylglycidyl ether.

<Second Unsaturated Compound (a3)>

The second unsaturated compound (a3) may be used in an amount rangingfrom 0 to 70 parts by weight, preferably from 0 to 60 parts by weight,and more preferably from 0 to 55 parts by weight based on 100 parts byweight of the alkali-soluble resin (A) used in the photosensitive resincomposition of the present invention.

Examples of the second unsaturated compound (a3) may include, but arenot limited to, alkyl (meth)acrylate, alicyclic (meth)acrylate, aryl(meth)acrylate, unsaturated dicarboxylic acid diester, hydroxyalkyl(meth)acrylate, (meth)acrylate polyether, and aryl vinyl compound.

Examples of the alkyl (meth)acrylate may include, but are not limitedto, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl(meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate,isobutyl (meth)acrylate, sec-butyl (meth)acrylate, and tert-butyl(meth)acrylate.

Examples of the alicyclic (meth)acrylate may include, but are notlimited to, cyclohexyl (meth)acrylate, 2-methylcyclohexyl(meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentyloxyethyl(meth)acrylate, isobornyl (meth)acrylate, and tetrahydrofurfuryl(meth)acrylate.

Examples of the aryl (meth)acrylate may include, but are not limited to,phenyl (meth)acrylate and benzyl (meth)acrylate.

Examples of the unsaturated dicarboxylic acid diester may include, butare not limited to, diethyl maleate, diethyl fumarate, and diethylitaconate.

Examples of the hydroxyalkyl (meth)acrylate may include, but are notlimited to, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl(meth)acrylate.

Examples of the (meth)acrylate polyether may include, but are notlimited to, poly(ethylene glycol) mono(meth)acrylate, and poly(propyleneglycol) mono(meth)acrylate.

Examples of the aryl vinyl compound may include, but are not limited to,styrene, α-methyl styrene, m-methylstyrene, p-methylstyrene, andp-methoxystyrene.

Examples of the second unsaturated compound (a3) may also include, butare not limited to, acrylonitrile, methacrylonitrile, vinyl chloride,vinylidene chloride, acrylamide, methacrylamide, vinyl acetate,1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,N-cyclohexylmaleimide, N-phenylmaleimide, N-benzylmaleimide,N-succinimidyl-3-maleimidobenzoate, N-succinimidyl-4-maleimidobutyrate,N-succinimidyl-6-maleimidohexanoate,N-succinimidyl-3-maleimidopropionate, and N-(9-acridinyl)maleimide.

Preferably, the second unsaturated compound (a3) is selected from thegroup consisting of methyl (meth)acrylate, butyl (meth)acrylate,2-hydroxyethyl (meth)acrylate, tert-butyl (meth)acrylate, benzyl(meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentyloxyethyl(meth)acrylate, styrene, p-methoxystyrene, and combinations thereof.

Examples of solvents for preparing the alkali-soluble resin (A) mayinclude, but are not limited to:

(1) alcohols, such as methanol, ethanol, benzyl alcohol,2-phenylethanol, and 3-phenyl-1-propanol;

(2) ethers, such as tetrahydrofuran;

(3) ethylene glycol ethers, such as ethylene glycol monopropyl ether,ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether;

(4) ethylene glycol alkyl ether acetates, such as ethylene glycol butylether acetate, ethylene glycol ethyl ether acetate, and ethylene glycolmethyl ether acetate;

(5) diethylene glycol ethers, such as diethylene glycol monomethylether, diethylene glycol monoethyl ether, diethylene glycol monobutylether, diethylene glycol dimethyl ether, diethylene glycol diethylether, and diethylene glycol methyl ethyl ether;

(6) dipropylene glycol ethers, such as dipropylene glycol monomethylether, dipropylene glycol monoethyl ether, dipropylene glycol dimethylether, dipropylene glycol diethyl ether, and dipropylene glycol methylethyl ether;

(7) propylene glycol monoalkyl ethers, such as propylene glycolmonomethyl ether, propylene glycol monoethyl ether, propylene glycolmonopropyl ether, and propylene glycol monobutyl ether;

(8) propylene glycol alkyl ether acetates, such as propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,propylene glycol monopropyl ether acetate, and propylene glycolmonobutyl ether acetate;

(9) propylene glycol alkyl ether propionates, such as propylene glycolmonomethyl ether propionate, propylene glycol monoethyl etherpropionate, propylene glycol monopropyl ether propionate, and propyleneglycol monobutyl ether propionate;

(10) aromatic hydrocarbons, such as toluene and xylene;

(11) ketones, such as methylethyl ketone, cyclohexanone, and diacetonealcohol; and

(12) esters, such as methyl acetate, ethyl acetate, propyl acetate,butyl acetate, ethyl lactate, methyl 2-hydroxy-isobutyrate, ethyl2-hydroxy-isobutyrate, methyl glycolate, ethyl glycolate, butylglycolate, methyl lactate, propyl lactate, butyl lactate, methyl3-hydroxypropanoate, ethyl 3-hydroxypropanoate, propyl3-hydroxypropanoate, butyl 3-hydroxypropanoate, methyl2-hydroxy-3-methylbutanoate, methyl methoxyacetate, ethylmethoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethylethoxyacetate, propyl ethoxyacetate, butyl ethoxyacetate, methylpropoxyacetate, ethyl propoxyacetate, propyl propoxyacetate, butylpropoxyacetate, methyl butoxyacetate, ethyl butoxyacetate, propylbutoxyacetate, butyl butoxyacetate, 3-methoxybutyl acetate, methyl2-methoxypropionate, ethyl 2-methoxypropionate, propyl2-methoxypropionate, butyl 2-methoxypropionate, methyl2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl 2-ethoxypropionate,butyl 2-ethoxypropionate, methyl 2-butoxypropionate, ethyl2-butoxypropionate, propyl 2-butoxypropionate, butyl 2-butoxypropionate,methyl 3-methoxypropionate, ethyl 3-methoxypropionate, propyl3-methoxypropionate, butyl 3-methoxypropionate, methyl3-ethoxypropionate, ethyl 3-ethoxypropionate, propyl 3-ethoxypropionate,butyl 3-ethoxypropionate, methyl 3-propoxypropionate, ethyl3-propoxypropionate, propyl 3-propoxypropionate, butyl3-propoxypropionate, methyl 3-butoxypropionate, ethyl3-butoxypropionate, propyl 3-butoxypropionate, and butyl3-butoxypropionate.

Preferably, the solvent for preparing the alkali-soluble resin (A) isselected from the group consisting of diethylene glycol dimethyl ether,propylene glycol monomethyl ether acetate, and a combination thereof.

The aforesaid examples of the solvent for preparing the alkali-solubleresin (A) can be used alone or as a mixture of two or more.

An initiator for preparing the alkali-soluble resin (A) may include, butis not limited to, azo compounds and peroxide compounds.

Examples of the azo compounds may include, but are not limited to,2,2′-azobisisobutyronitrile, 2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile),2,2′-azobis(2-methylbutyronitrile), 4,4′-azobis(4-cyanovaleric acid),dimethyl-2,2′-azobis(2-methylpropionate), and2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile).

Examples of the peroxide compounds may include, but are not limited to,benzoyl peroxide, lauroyl peroxide, tert-butyl peroxypivalate,1,1-di(tert-butylperoxy)cyclohexane, and hydrogen peroxide.

Preferably, the molecular weight of the alkali-soluble resin (A) isadjustable by using a single resin or using two or more resins.Preferably, the molecular weight of the alkali-soluble resin (A) rangesfrom 3,000 to 100,000, more preferably from 4,000 to 80,000, and evenmore preferably from 5,000 to 60,000.

[O-Naphthoquinonediazidesulfonic Acid Ester (B)]

There is no particular limitation to the o-naphthoquinonediazidesulfonicacid ester (B) for the photosensitive resin composition according to thepresent invention. The o-naphthoquinonediazidesulfonic acid ester (B)may be a partially or completely esterified compound. Preferably, theo-naphthoquinonediazidesulfonic acid ester (B) is obtained via areaction of o-naphthoquinonediazidesulfonic acid or salt thereof with ahydroxyl compound. More preferably, the o-naphthoquinonediazidesulfonicacid ester (B) is obtained via a reaction ofo-naphthoquinonediazidesulfonic acid or salt thereof with a polyhydroxylcompound.

Examples of the o-naphthoquinonediazidesulfonic acid may include, butare not limited to, o-naphthoquinonediazide-4-sulfonic acid,o-naphthoquinonediazide-5-sulfonic acid, ando-naphthoquinonediazide-6-sulfonic acid. A non-limiting example of thesalt of o-naphthoquinonediazidesulfonic acid may be halide ofo-naphthoquinonediazidesulfonic acid.

Examples of the hydroxyl compound may include, but are not limited to:

(1) hydroxybenzophenones: such as 2,3,4-trihydroxybenzophenone,2,4,4′-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone,2,3,4,4′-tetrahydroxybenzophenone, 2,4,2′,4′-tetrahydroxybenzophenone,2,4,6,3′,4′-pentahydroxybenzophenone,2,3,4,2′,4′-pentahydroxybenzophenone,2,3,4,2′,5′-pentahydroxybenzophenone,2,4,5,3′,5′-pentahydroxybenzophenone, and2,3,4,3′,4′,5′-hexahydroxybenzophenone.

(2) hydroxyaryl compounds: a nonlimiting example of the hydroxyarylcompound is represented by Formula (a):

wherein

R^(m), R^(n), and R^(o) independently represent a hydrogen atom or aC₁-C₆ alkyl group;

R^(p), R^(q), R^(r), R^(s), R^(t), and R^(u) independently represent ahydrogen atom, a halogen atom, a C₁-C₆ alkyl group, a C₁-C₆ alkoxygroup, a C₁-C₆ alkenyl group, or a cycloalkyl group;

R^(v) and R^(w) independently represent a hydrogen atom, a halogen atom,or a C₁-C₆ alkyl group;

x, y, and z independently denote an integer ranging from 1 to 3; and

k is 0 or 1.

Examples of the hydroxyaryl compound represented by Formula (a) include,but are not limited to, tri(4-hydroxyphenyl)methane,bis(4-hydroxy-3,5-dimethylphenyl)-4-hydroxyphenylmethane,bis(4-hydroxy-3,5-dimethylphenyl)-3-hydroxyphenylmethane,bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane,bis(4-hydroxy-2,5-dimethylphenyl)-4-hydroxyphenylmethane,bis(4-hydroxy-2,5-dimethylphenyl)-3-hydroxyphenylmethane,bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane,bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane,bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane,bis(4-hydroxy-3,5-dimethylphenyl)-2,4-dihydroxyphenylmethane,bis(4-hydroxy-2,5-dimethylphenyl)-2,4-dihydroxyphenyl methane,bis(4-hydroxyphenyl)-3-methoxy-4-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxyphenyl)-2-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxyphenyl)-4-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-2-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-3-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-4-hydroxyphenylmethane,bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-3,4-dihydroxyphenylmethane,bis(3-cyclohexyl-6-hydroxyphenyl)-3-hydroxyphenylmethane,bis(3-cyclohexyl-6-hydroxyphenyl)-4-hydroxyphenylmethane,bis(3-cyclohexyl-6-hydroxyphenyl)-2-hydroxyphenylmethane,bis(3-cyclohexyl-6-hydroxy-4-methylphenyl)-2-hydroxyphenylmethane,bis(3-cyclohexyl-6-hydroxy-4-methylphenyl)-4-hydroxyphenylmethane,bis(3-cyclohexyl-6-hydroxy-4-methylphenyl)-3,4-dihydroxyphenylmethane,1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene,and1-[1-(3-methyl-4-hydroxyphenyl)isopropyl]-[1,1-bis(3-methyl-4-hydroxyphenyl)ethyl]benzene.

(3) (hydroxyphenyl)hydrocarbons: a non-limiting example of the(hydroxyphenyl)hydrocarbons is represented by Formula (b):

wherein

R^(x) and R^(y) independently represent a hydrogen atom or a C₁-C₆ alkylgroup; and

x′ and y′ independently represent an integer ranging from 1 to 3.

Examples of the (hydroxyphenyl)hydrocarbon compound represented byFormula (b) may include, but are not limited to,2-(2,3,4-trihydroxyphenyl)-2-(2′,3′,4′-trihydroxyphenyl)propane,2-(2,4-dihydroxyphenyl)-2-(2′,4′-dihydroxyphenyl)propane,2-(4-hydroxyphenyl)-2-(4′-hydroxyphenyl)propane,bis(2,3,4-trihydroxyphenyl)methane, and bis(2,4-dihydroxyphenyl)methane.

(4) other aromatic hydroxyl compounds: such as phenol, p-methoxyphenol,dimethylphenol, hydroquinone, bisphenol A, naphthol, pyrocatechol,pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl ether, gallic acid,and partially esterified or partially etherified gallic acid.

The aforesaid examples of the hydroxyl compounds can be used alone or asa mixture of two or more.

Preferably, the hydroxyl compound is selected from the group consistingof1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene,2,3,4-trihydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone, andcombinations thereof.

The reaction of o-naphthoquinonediazidesulfonic acid or salt thereofwith the hydroxyl compound is often conducted in an organic solvent suchas dioxane, N-pyrrolidone, acetamide, and the like, in the presence ofan alkali condensation agent such as triethanolamine, alkali carbonate,alkali hydrogen carbonate, and the like.

Preferably, the esterification rate of theo-naphthoquinonediazidesulfonic acid ester (B) is greater than 50%. Thatis, more than 50% by mole of the hydroxyl groups contained in thehydroxyl compound undergoes an esterification reaction witho-naphthoquinonediazidesulfonic acid or salt thereof, based on 100% bymole of the total hydroxyl groups contained in the hydroxyl compound.More preferably, the esterification rate of the o-naphthoquinonediazidesulfonic acid ester (B) is greater than 60%.

The o-naphthoquinonediazidesulfonic acid ester (B) is used in an amountranging from 10 parts by weight to 50 parts by weight, preferably from15 parts by weight to 50 parts by weight, and more preferably from 15parts by weight to 45 parts by weight based on 100 parts by weight ofthe alkali-soluble resin (A) used in the photosensitive resincomposition according to the present invention.

[Silsesquioxane (C)]

A silsesquioxane (C) has at least two thiol groups in a molecule and isobtained by subjecting to condensation a silane material which includesa thiol-group-containing silane represented by formula (I):

R^(aSi(OR) _(b))₃  (I)

wherein

R^(a) represents a C₁-C₈ organic group that contains a thiol group andthat is free from an aromatic group, or an organic group that contains athiol group and an aromatic group; and

R^(b) independently represents hydrogen, a C₁-C₆ alkyl group, a C₁-C₆acyl group, or a C₆-C₁₅ aromatic group.

When the photosensitive resin composition does not contain thesilsesquioxane (C) having at least two thiol groups in a molecule, theprotective film formed from the photosensitive resin composition has apoor cross-sectional shape and high linear thermal expansioncoefficient. Since the thiol group of the silsesquioxane (C) may reactwith reactive functional groups of other components contained in thephotosensitive resin composition, the protective film formed from thephotosensitive resin composition has good cross-sectional shape and lowlinear thermal expansion coefficient. Examples of the reactivefunctional group may be, but are not limited to, an unsaturated bond, ahydroxyl group, an epoxy group, and combinations thereof.

Preferably, R^(a) represents a C₁-C₈ aliphatic hydrocarbon groupcontaining a thiol group, a C₁-C₈ alicyclic hydrocarbon group containinga thiol group, or a C₆-C₁₄ aromatic hydrocarbon group containing a thiolgroup.

In the definition of R^(b), examples of the alkyl group include, but arenot limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, andcombinations thereof. A non-limiting example of the acyl group isacetyl. A non-limiting example of the aryl group is phenyl.

Thiol-Group-Containing Silane Represented by Formula (I):

Examples of the silane represented by Formula (I) include, but are notlimited to, 3-mercaptopropyltrimethoxysilane,3-mercaptopropyltriethoxysilane, 3-mercaptopropyltriisopropoxysi lane,3-mercaptopropyltri-n-butoxysilane,1,4-dimercapto-2-(trimethoxysilyl)butane,1,4-dimercapto-2-(triethoxysilyl)butane,1,4-dimercapto-2-(triisopropoxysilyl)butane,1,4-dimercapto-2-(tributoxysilyl)butane,2-mercaptomethyl-3-mercaptopropyltrimethoxysilane,2-mercaptomethyl-3-mercaptopropyltriethoxysilane,2-mercaptomethyl-3-mercaptoisopropyltripropoxysilane,2-mercaptomethyl-3-mercaptopropyltri-n-butoxysilane,1,2-dimercaptoethyltrimethoxysilane, 1,2-dimercaptoethyltriethoxysilane,1,2-dimercaptoethyltriisopropoxysilane, and1,2-dimercaptoethyltri-n-butoxysilane. The aforesaid examples of thethiol-group-containing silane represented by Formula (I) may be usedalone or in admixture. Preferably, the thiol-group-containing silanerepresented by Formula (I) is 3-mercaptopropyltrimethoxysilane, that hashigh reactivity in hydrolysis reaction and is widely available.

Preferably, the silane material further includes a cross-linkingcompound. The cross-linking compound has an effect to regulate acrosslink density of the silsesquioxane (C). The cross-linking compoundis selected from the group consisting of monoalkoxysilane,dialkoxysilane, trialkoxysilane, tetraalkoxysilane, tetraalkoxytitanium, and tetraalkoxy zirconium.

The use of trialkoxysilane can help to regulate the number of thiolgroup of the silsesquioxane (C). The use of tetraalkoxy titanium ortetraalkoxy zirconium can help to improve a refractive index of a curedproduct formed from the silsesquioxane (C).

Examples of monoalkoxysilane include, but are not limited to,trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane,triethylethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, andcombinations thereof.

Examples of dialkoxysilane include, but are not limited to,dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane,diethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane,methylphenyldimethoxysilane, methylphenyldiethoxysilane,3-mercaptopropylmethyldimethoxysilane, and combinations thereof.

Examples of trialkoxysilane include, but are not limited to,methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane,ethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, andcombinations thereof.

Examples of tetraalkoxysilane include, but are not limited to,tetramethoxysilane, tetraethoxysilane, tetraisopropoxyslane,tetra-n-butoxysilane, and combinations thereof.

Examples of tetraalkoxy titanium include, but are not limited to,tetramethoxy titanium, tetraethoxy titanium, tetraisopropoxy titanium,tetra-n-butoxy titanium, and combinations thereof.

Examples of tetraalkoxy zirconium include, but are not limited to,tetraethoxy zirconium, tetraisopropoxy zirconium, tetra-n-butoxyzirconium, and combinations thereof.

In addition to tetraalkoxy titanium and tetraalkoxy zirconium, othermetal alkoxides may be used.

Preparation of Silsesquioxane (C): 1. Hydrolysis Process:

A catalyst can be added while the silane material undergoes a hydrolysisprocess. There is no particular limitation to the catalyst forhydrolysis, and the general catalyst can be used. Preferably, thecatalyst is formic acid that has high catalyst activity and canfacilitate a condensation reaction.

The catalyst is used in an amount ranging preferably from 0.1 to 25parts by weight, and more preferably from 1 to 10 parts by weight basedon 100 parts by weight of the silane material. When the amount of thecatalyst is above 0.1 part by weight, the silane material can behydrolyzed sufficiently. When the amount of the catalyst is below 25parts by weight, the storage stability of the silsesquioxane (C) isbetter, and the catalyst is easily removed in subsequent steps.

The reaction temperature and the reaction time for the hydrolysisreaction are adjusted depending on a reactivity of the selected silanematerial. The reaction temperature for the hydrolysis reaction rangespreferably from 0° C. to 100° C. and more preferably from 20° C. to 60°C. Preferably, the reaction time for the hydrolysis reaction ranges from1 minute to 2 hours.

A solvent may or may not be used in the hydrolysis process depending onthe reactivity of the silane material. For example, if the reactivity ofthe silane material is low, then the solvent is not used. There is noparticular limitation to the solvent. Examples of the solvent include,but are not limited to, methanol, ethanol, n-propanol, isopropanol,n-butanol, isobutanol, 2-methyl-2-propanol, acetone, methyl ethylketone, methyl isobutyl ketone, diacetone alcohol, propylene glycolmonomethyl ether, propylene glycol methyl ether acetate,tetrahydrofuran, dioxacyclohexane, acetonitrile, and combinationsthereof. Preferably, the solvent used in the hydrolysis process is thesame one used in the condensation process.

2. Condensation Process:

Considering that the condensation occurs between the hydroxyl groupsgenerated by hydrolysis and between the hydroxyl groups and the alkoxygroups unreacted after hydrolysis, the hydrolysis reaction is conductedsuch that the ratio of a molar number of the hydroxyl group generated byhydrolysis to a molar number of total alkoxy groups in the silanematerial is preferably above 0.5 and more preferably above 0.8. Duringthe condensation process, water is generated via a reaction between thehydroxyl groups generated by hydrolysis, and alcohol is generated via areaction between the unreacted alkoxy groups after hydrolysis and thehydroxyl groups. The silsesquioxane (C) having at least two thiol groupsin a molecule is generated and is vitrified.

The catalyst may be added during the condensation process. There is noparticular limitation to the catalyst, and the general catalyst can beused. Preferably, the catalyst is formic acid that has high catalystactivity so that it can serve as the catalyst for both hydrolysis andcondensation. The reaction temperature and the reaction time for thecondensation are adjusted depending on the reactivity of the selectedsilane material. The reaction temperature ranges preferably from 40° C.to 150° C. and more preferably from 60° C. to 100° C. The reaction timeranges preferably 30 minutes to 12 hours.

The condensation reaction is conducted such that a ratio of a totalmolar number of the unreacted hydroxyl groups and the unreacted alkoxygroups to a molar number of total alkoxy groups in the silane materialis preferably below 0.3 and more preferably below 0.2. Theaforementioned ratio is used in order to prevent the unreacted hydroxylgroups and the unreacted alkoxy groups from condensing after thesilsesquioxane (C) is formed, which may cause gelation during storage,and to prevent the silsesquioxane (C) from further condensing aftercuring, which may cause cracking.

In the condensation process, the concentration of the silane materialranges preferably from 2 wt % to 80 wt % and more preferably from 15 wt% to 60 wt %. This can prevent gelation during the condensation processand prevent excess molecular weight of the silsesquioxane (C) so as toimprove storage stability of the silsesquioxane (C).

Preferably, when the condensation process is conducted, the solvent thatis used has a boiling point higher than that of water and alcoholgenerated from condensation so as to remove the water and alcoholeasily. The solvent may be used alone or in admixture. Preferably, thecatalyst is removed after the condensation process so as to improvestorage stability of the silsesquioxane (C). There is no particularlimitation to the method for removing the catalyst, and any appropriatemethod well known in the art may be chosen depending on the specificcatalyst used in the condensation process. Examples of the method forremoving the catalyst include, but are not limited to, heating above theboiling point of the catalyst, or reducing the pressure. When thecatalyst is formic acid, it can be removed easily by any of theaforementioned methods.

Commercially available products of the silsesquioxane (C) having atleast two thiol groups in a molecule may include, but are not limitedto, COMPOCERAN SQ-101, COMPOCERAN SQ-102, COMPOCERAN SQ-102-1,COMPOCERAN SQ-103, COMPOCERAN SQ105, COMPOCERAN SQ105-1, and COMPOCERANSQ105-7 available from Arakawa Chemical Industries, Ltd.

The silsesquioxane (C) is used in an amount ranging from 0.5 to 20 partsby weight, preferably from 1 to 15 parts by weight, and more preferablyfrom 3 to 15 parts by weight based on 100 parts by weight of thealkali-soluble resin (A) used in the photosensitive resin compositionaccording to the present invention.

[Solvent (D)]

There is no particular limitation to the solvent (D) for thephotosensitive resin composition of the present invention so long as thesolvent (D) can dissolve other components in the photosensitive resincomposition and is highly volatile so as to be evaporated easily underatmospheric pressure with a small amount of provided heat. Preferably,the solvent (D) has a boiling temperature that is lower than 150° C.under atmospheric pressure. Examples of the solvent (D) may include, butare not limited to:

(i) aromatic solvents, such as benzene, toluene, and xylene;

(ii) alcohols, such as methanol and ethanol;

(iii) ethers, such as ethylene glycol monopropyl ether, diethyleneglycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethylether, ethylene glycol monoethyl ether, diethylene glycol methyl ether,diethylene glycol ethyl ether, and diethylene glycol butyl ether;

(iv) esters, such as ethylene glycol monomethyl ether acetate, ethyleneglycol monoethyl ether acetate, propylene glycol monomethyl etheracetate, propylene glycol monoethyl ether acetate, propylene glycolmonopropyl ether acetate, and ethyl 3-ethoxypropionate (abbreviated asEEP); and

(v) ketones, such as methyl ethyl ketone, and acetone.

Preferably, the solvent (D) is selected from the group consisting ofdiethylene glycol dimethyl ether, propylene glycol monomethyl etheracetate, ethyl 3-ethoxypropionate, and combinations thereof inconsideration of the storage stability of the photosensitive resincomposition of the present invention.

Preferably, the solvent (D) is used in an amount ranging generally from100 parts by weight to 800 parts by weight, preferably from 150 parts byweight to 750 parts by weight, and more preferably from 200 parts byweight to 600 parts by weight based on 100 parts by weight of thealkali-soluble resin (A) used in the photosensitive resin compositionaccording to the present invention.

[Additives (E)]

The photosensitive resin composition of the present invention mayoptionally include additives (E). Examples of the additives (E) mayinclude, but are not limited to, a filler, a polymer other than thealkali-soluble resin (A), a UV absorber, a anticoagulant, a surfactant,an adhesion promoter, a stabilizer, a thermal resistance enhancer, acuring accelerator, and combinations thereof.

There is no specific limitation for the filler. Preferably, the filleris aluminum or a glass material.

Preferably, the polymer other than the alkali-soluble resin (A) ispolyvinyl alcohol, polyethylene glycol monoalkyl ether, orpolyfluoroalkyl acrylate.

As for the UV absorber, there is no specific requirement for the speciesthereof. Preferably, the UV absorber is2-(3-tert-butyl-5-methyl-2-hydroxyphenyl)-5-chlorophenyl azide or alkoxyphenyl ketone.

Preferably, the anticoagulant is, but not limited to, sodiumpolyacrylate.

Examples of the surfactant may include, but are not limited to, afluorine surfactant or a silicone surfactant which may be used alone orin combination. The surfactant is used to enhance the coating propertyof the photosensitive resin composition of the present invention.

Preferably, the fluorine surfactant is a compound having a fluoroalkylor fluoroalkenyl group at a terminal, main chain, and side chain.Examples of the fluorine surfactant may include, but are not limited to,1,1,2,2-tetrafluorooctyl(1,1,2,2-tetrafluoropropyl)ether,1,1,2,2-tetrafluorooctylhexyl ether, octaethylene glycoldi(1,1,2,2-tetrafluorobutyl)ether, hexaethylene glycol(1,1,2,2,3,3-hexafluoropentyl)ether, octapropylene glycoldi(1,1,2,2,-tetrafluorobutyl)ether, hexapropylene glycol(1,1,2,2,3,3-hexafluoropentyl)ether, sodium perfluorododecyl sulfate,1,1,2,2,8,8,9,9,10,10-decafluorododecane, 1,1,2,2,3,3-hexafluorodecane,sodium fluoroalkylbenzene sulfonate, sodium fluoroalkyl phosphonate,sodium fluoroalkylcarboxylate, fluoroalkylpolyoxyethylene ether,diglycerin tetrakis(fluoroalkylpolyoxyethylene ether),fluoroalkylammonium iodide, fluoroalkylbetain, fluoroalkylpoly(propyleneoxide) ether, perfluoroalkylpoly(propylene oxide) ether, andperfluoroalkyl alkanol.

Commercially available products of the fluorine surfactant includeBM-1000 and BM-1100 available from BM CHEMIE Co., Ltd.; Megafac F142D,Megafac F172, Megafac F173, Megafac F183, Megafac F178, Megafac F191,Megafac F471 and Megafac F476 available from Dainippon Ink and ChemicalsInc.; Fluorad FC170C, Fluorad FC-171, Fluorad FC-430 and Fluorad FC-431available from Sumitomo 3M Limited; Surflon S-112, Surflon S-113,Surflon S-131, Surflon S-141, Surflon S-145, Surflon S-382, SurflonSC-101, Surflon SC-102, Surflon SC-103, Surflon SC-104, Surflon SC-105and Surflon SC-106 available from Asahi Glass Co., Ltd.; F-TOP EF301,F-TOP EF303, and F-TOP EF352 available from Shin Akita Kasei Co., Ltd.;and Ftergent FT-100, FT-110, FT-140A, FT-150, FT-250, FT-251, FTX-251,FTX-218, FT-300, FT-310, and FT-400S available from NEOS Co., Ltd.

Commercially available products of the silicone surfactant include, butare not limited to, Toray Silicon DC3PA, DC7PA, SH11PA, SH21PA, SH28PA,SH29PA, SH30PA, SH-190, SH-193, SZ-6032, SF-8427, SF-8428, DC-57, andDC-190 available from Dow Corning Toray Silicone Co., Ltd.; andTSF-4440, TSF-4300, TSF-4445, TSF-4446, TSF-4460, and TSF-4452 availablefrom GE Toshiba Silicone Co., Ltd.

Other than the fluorine surfactant and the silicone surfactant, examplesof the surfactant which can be used in the photosensitive resincomposition of the present invention can also include: (i)polyoxyethylene alkylethers, such as polyoxyethylene lauryl ether,polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; (ii)polyoxyethylene aryl ethers, such as polyoxyethylene n-octylphenyl etherand polyoxyethylene n-nonylphenol ether; (iii) polyoxyethylenedialkylesters, such as polyoxyethylene dilaurate and polyoxyethylenedistearate; and (iv) non-ionic surfactants, such as KP341 available fromShietsu Chemical Co., Ltd., and Polyflow No. 57 and Polyflow No. 95available from Kyoeisya Chemical Co., Ltd.

The adhesion promoter can be used for further improving adhesion of theprotective film made from the photosensitive resin composition of thepresent invention to a substrate. The adhesion promoter may include, butis not limited to, functional silane compounds which preferably containa carboxyl group, an alkenyl group, an isocynate group, an epoxy group,an amino group, a mercapto group, or halogen. Examples of the silanecompound may include, but are not limited to,p-hydroxyphenyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane,3-acryloxypropyltrimethoxysilane, vinyltriacetoxysilane,vinyltrimethoxysilane, vinyltriethoxysilane,vinyltri(2-methoxyethoxy)silane, γ-isocyanatopropyltriethoxysilane,3-glycidylpropyltrimethyoxysilane (such as KBM403, commerciallyavailable from Shietsu Chemical Co., Ltd.),2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-glycidylpropyldimethylmethoxysilane, 3-amimopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimeth oxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, and3-chloropropylmethyldimethoxysilane. The aforementioned examples can beused alone or in a mixture of two or more.

The stabilizer may include sulfides, quinones, hydroquinones, polyoxycompounds, amines, nitro compounds, nitroso compounds, and the like.Examples of the stabilizer may include, but are not limited to,4-methoxyphenol, N-nitroso-N-phenylhydroxylamine aluminum,2,2′-thio-bis(4-methyl-6-tert-butylphenol), and 2,6-di-tert-butylphenol.

The thermal resistance enhancer may include anN-(alkoxymethyl)glycoluril compound, an N-(alkoxymethyl)melaminecompound, and the like. Examples of the N-(alkoxymethyl)glycolurilcompound may include, but are not limited to,N,N,N′,N′-tetra(methoxymethyl)glycoluril,N,N,N′,N′-tetra(ethoxymethyl)glycoluril,N,N,N′,N′-tetra(n-propoxymethyl)glycoluril,N,N,N′,N′-tetra(i-propoxymethyl)glycoluril,N,N,N′,N′-tetra(n-butoxymethyl)glycoluril, andN,N,N′,N′-tetra(t-butoxymethyl)glycoluril, and is preferablyN,N,N′,N′-tetra(methoxymethyl)glycoluril. Examples of theN-(alkoxymethyl)melamine compound may include, but are not limited to,N,N,N′,N′,N″,N″-hexa(methoxymethyl)melamine,N,N,N′,N′,N″,N″-hexa(ethoxymethyl)melamine,N,N,N′,N′,N″,N″-hexa(n-propoxymethyl)melamine,N,N,N′,N′,N″,N″-hexa(i-propoxymethyl)melamine,N,N,N′,N′,N″,N″-hexa(n-butoxymethyl)melamine, andN,N,N′,N′,N″,N″-hexa(t-butoxymethyl)melamine, and is preferablyN,N,N′,N′,N″,N″-hexa(methoxymethyl)melamine. Commercially availableproducts of the N-(alkoxymethyl)melamine compound include NIKARAKKUN-2702 and MW-30M available from Sanwa chemical Co., Ltd.

The curing accelerator is adopted for lowering the linear thermalexpansion coefficient of the products made from the photosensitive resincomposition according to the present invention. Examples of the curingaccelerator may include, but are not limited to: (1) an urethane(meth)acrylate compound having at least one (meth)acryloyl group:commercially available products of which may include, but are notlimited to, Art Resin UN-3320HC and Art Resin UN-3320HS available fromNegami Industry Co., Ltd.; NK Oligo U-6HA available from Shin-NakamuraChemical Industry Co., Ltd.; Shiko UV-1700B and Shiko UV-7605B availablefrom Nippon Synthetic Chemical Industry Co., Ltd.; (2) anepoxy-containing compound, for example, but not limited to, bisphenoldiglycidyl ethers, such as bisphenol A diglycidyl ether, bisphenol Fdiglycidyl ether, bisphenol S diglycidyl ether, hydrogenated bisphenol Adiglycidyl ether, hydrogenated bisphenol F diglycidyl ether,hydrogenated bisphenol AD diglycidyl ether, brominated bisphenol Adiglycidyl ether, brominated bisphenol F diglycidyl ether, andbrominated bisphenol S diglycidyl ether; (3) guanamines, such asmelamine, acetoguanamine, and benzoguanamine; (4) amines, such asdicyandiamide, benzyldimethylamine,4-(dimethylamino)-N,N-dimethylbenzylamine,4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine;and (5) imidazole derivatives and salts thereof, such as, imidazole,2-methyl imidazole, 2-ethyl imidazole, 2-ethyl-4-methyl imidazole,2-phenyl imidazole, 4-phenyl imidazole, 1-cyanoethyl-2-ethyl imidazole,and 1-(2-cyanoethyl)-2-ethyl-4-methyl imidazole.

The amount of the additives (E) used in the photosensitive resincomposition of the present invention may be adjusted based on theknowledge of people having ordinary skill in the art, so long as theintended properties of the photosensitive resin composition are notimpaired. The amount of the additives (E) used in the photosensitiveresin composition ranges preferably from 0 to 30 parts by weight, morepreferably from 0 to 25 parts by weight, and even more preferably from 0to 20 parts by weight based on 100 parts by weight of the alkali-solubleresin (A) used in the photosensitive resin composition.

To prepare the photosensitive resin composition according to the presentinvention, the alkali-soluble resin (A), theo-naphthoquinonediazidesulfonic acid ester (B), the silsesquioxane (C),the solvent (D), and optionally the additives (E) are placed into astirrer and are stirred until a uniform solution is formed.

A protective film of the present invention is formed by coating thephotosensitive resin composition onto a substrate, followed bypre-baking, exposing, developing, and post-baking treatments.

The photosensitive resin composition is applied onto the substrate byspray-coating, roller-coating, spin-coating, slit-coating, bar-coating,or the like (preferably spin-coating or slit-coating), and then issubjected to the pre-baking treatment to remove the solvent therein soas to form a prebaked film. The conditions of the pre-baking treatmentdepend on the types and the formulating ratio of the components in thephotosensitive resin composition according to the present invention.However, the prebaking treatment is usually conducted at a temperatureranging from 60° C. to 110° C. for 30 seconds to 15 minutes. Preferably,the prebaked film has a thickness ranging from 3 to 6 μm.

After the pre-baking treatment, the prebaked film is subjected to theexposing treatment via a photomask by using, for example, UV light,far-UV light, X ray, charged particle beam, or the like. For example,the UV light may be g-line (wavelength of 436 nm), h-line, or i-line(wavelength of 365 nm), the far-UV light may be KrF excimer laser, the Xray may be synchrotron radiation, and the charged particle beam may bean electron beam. Preferably; the UV light is adopted, and morepreferably, the g-line or the i-line is adopted. Examples of a devicefor providing the UV light may include, but are not limited to, a highpressure mercury lamp, an ultra-high pressure mercury lamp, and a metalhalide lamp. Preferably, the exposure dose ranges from 50 to 1500 J/m².

After the exposing treatment, the developing treatment is conducted byimmersing the prebaked film into a developing solution for 30 seconds to2 minutes, so as to obtain a developed film that is formed with adesired pattern. Examples of the developing solution include: (1)inorganic alkali compounds, such as sodium hydroxide, potassiumhydroxide, sodium carbonate, sodium silicate, sodium metasilicate, andammonia; (2) primary aliphatic amines, such as ethylamine, andn-propylamine; (3) secondary aliphatic amines, such as diethylamine, anddi(n-propyl)amine; (4) tertiary aliphatic amines, such astrimethylamine, N,N-diethylmethylamine, 1N,N-dimethylethylamine, andtriethylamine: (5) tertiary alicyclic acids, such as pyrrole,piperidine, N-methyl piperidine,N-methyl-1,8-diazabicyclo[5.4.0]undec-7-ene, and1,5-diazabicyclo[4.3.0]non-5-ene; (6) tertiary aromatic amines, such aspyridine, methylpyrimidine, dimethylpyridine, and quinoline; and (7)quaternary ammonium alkali compounds, such as an aqueoustetramethylammonium hydroxide solution and an aqueous tetraethylammoniumhydroxide solution.

Moreover, water-soluble organic solvents and/or surfactants, such asmethanol and ethanol, may be optionally added into the developingsolution, and examples of the method of the developing treatment mayinclude, but are not limited to, puddle developing, impregnationdeveloping (with or without sonication), and rinse developing.

The developing solution is removed by rinsing the developed film on thesubstrate with water, followed by drying with compressed air or nitrogengas. Preferably, a post-exposure treatment is conducted using a highpressure mercury lamp for decomposing the residue of theo-naphthoquinonediazidesulfonic acid ester (B) in a developed film. Morepreferably, the exposure dose of the post-exposure treatment ranges from2000 to 5000 J/m².

Thereafter, the post-baking treatment is conducted via a heating device,such as a heating plate or an oven, with a temperature ranging from 120°C. to 250° C., so as to form the protective film of the presentinvention. The baking period of the post-baking treatment may varydepending on the heating device. As for the heating plate, the heatingtime of the post-baking treatment ranges from 5 minutes to 30 minutes.As for the oven, the heating time of the post-baking treatment rangesfrom 30 minutes to 90 minutes.

Examples of the substrate suitable for the present invention include analkali-free glass, a soda-lime glass, a Pyrex glass, a quartz glass, aglass coated with a transparent conductive film thereon, and the like,which is commonly used in a liquid crystal display; and a photoelectricconversion substrate (for example, a silicon substrate) used in asolid-state image sensor.

An element including the substrate and the protective film formed fromthe photosensitive resin composition of the present invention can beused in a display device, a semiconductor device, an optical waveguidedevice, and the like.

The following examples are provided to illustrate the preferredembodiments of the invention, and should not be construed as limitingthe scope of the invention.

EXAMPLES Preparation of Alkali-Soluble Resin (A) Synthesis Example A-1

A 1000 ml four-necked flask, which is equipped with a nitrogen inlet, astirrer, a heater, a condenser, and a thermometer, was introduced withnitrogen gas and was added with methacrylic acid (referred as MMA, 10parts by weight), glycidyl methacrylate (referred as GMA, 65 parts byweight), dicyclopentanyl methacrylate (referred as FA-513M, 15 parts byweight), styrene (referred as SM, 10 parts by weight), and diethyleneglycol dimethyl ether as a solvent (referred as Diglyme, 240 parts byweight) to form a mixture.

When the four-necked flask was filled with nitrogen gas, the mixture wasstirred and heated up to 85° C. in an oil bath. A catalyst solution (3.0parts by weight of 2,2′-azobis(2,4-dimethylvaleronitrile)(referred asADVN) dissolved in 20 parts by weight of Diglyme) was divided into 5parts and was added sequentially into the four-necked flask part by partwithin an hour for inducing a polymerization reaction. Thepolymerization reaction was then conducted at 70° C. for 5 hours. Afterthe polymerization reaction was completed, the product was taken out ofthe flask, followed by devolatilizing the solvent, so as to obtain analkali-soluble resin (A-1).

Synthesis Example A-2

A 1000 ml four-necked flask, which is equipped with a nitrogen inlet, astirrer, a heater, a condenser, and a thermometer, was introduced withnitrogen gas and was added with 2-methacryloyloxyethyl succinatemonoester (referred as HOMS, 40 parts by weight),3,4-epoxycyclohexylmethyl methacrylate (referred as EC-MAA, 25 parts byweight), 2-hydroxyethyl methacrylate (referred as HEMA, 5 parts byweight), FA-513M (10 parts by weight), SM (20 parts by weight), andpropylene glycol monomethyl ether acetate as a solvent (referred asPGMEA, 240 parts by weight) to form a mixture.

When the four-necked flask was filled with nitrogen gas, the mixture wasstirred and heated up to 85° C. in an oil bath. A catalyst solution (2.4parts by weight of ADVN dissolved in 20 parts by weight of PGMEA) wasdivided into 5 parts and was added sequentially into the four-neckedflask part by part within one hour for inducing a polymerizationreaction. The polymerization reaction was then conducted at 70° C. for 6hours. After the polymerization reaction was completed, the product wastaken out of the flask, followed by devolatilizing the solvent, so as toobtain an alkali-soluble resin (A-2).

Synthesis Example A-3

A 1000 ml four-necked flask, which is equipped with a nitrogen inlet, astirrer, a heater, a condenser, and a thermometer, was introduced withnitrogen gas and was added with MMA (25 parts by weight), GMA (20 partsby weight), EC-MMA (20 parts by weight), HEMA (10 parts by weight),FA-513M (10 parts by weight), benzyl methacrylate (referred as BzMA, 15parts by weight), Diglyme (as a solvent, 200 parts by weight), and PGMEA(as a solvent, 40 parts by weight) to form a mixture.

When the four-necked flask was filled with nitrogen gas, the mixture wasthen stirred and heated up to 85° C. under an oil bath. A catalystsolution (3 parts by weight of 2,2′-azobis(2-methylbutyronitrile)(referred as AMBN) dissolved in 20 parts by weight of Diglyme) wasdivided into 5 parts and was added sequentially into the four-neckedflask part by part within an hour for inducing a polymerizationreaction. The polymerization reaction was conducted at 70° C. for 5hours. After the polymerization reaction was completed, the product wastaken out of the flask, followed by devolatilizing the solvent so as toobtain an alkali-soluble resin (A-3).

Preparation of Photosensitive Resin Composition Example 1

A 500 ml three-necked flask was added with the alkali-soluble resin(A-1) (100 parts by weight), an o-naphthoquinonediazidesulfonic acidester (DPAP200, commercially available from DKC with 67% of averagedegree of esterification, 30 parts by weight) that is obtained fromreacting o-naphthoquinonediazide-5-sulfonic acid with1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene, COMPOCERAN SQ-101 (10 parts by weight, commercially available fromArakawa Chemical Industries, Ltd.), and PGMEA (400 parts by weight).Stirring was conducted using a shaker so as to obtain a photosensitiveresin composition. The photosensitive resin composition was subjected tothe following evaluations and the results are listed in Table 2.

Examples 2 to 8 and Comparative Examples 1 to 3

The method for preparing the photosensitive resin composition of each ofExamples 2 to 8 and Comparative Examples 1 to 3 was similar to that ofExample 1. The only difference resides in the components and the amountsthereof in the photosensitive resin composition, which are shown inTable 2. The photosensitive resin composition of each of Examples 2 to 8and Comparative Examples 1 to 3 was subjected to the followingevaluations and the results are listed in Table 2.

Preparation of Patterned Protective Film Application Example 1

The photosensitive resin composition of Example 1 was spin-coated onto a100×100×0.7 mm³ glass substrate to obtain a coated film that has athickness of about 2 Thereafter, the coated film was prebaked at 110° C.for 2 minutes, followed by being exposed with UV of 200 mJ/cm² exposuredose (AG500-4N, manufactured by M&R Nano Technology) through a patternmask and immersing in a developing solution (0.4 wt % oftetramethylammonium hydroxide) at 23° C. for one minute to remove theexposed part of the coated film. The coated film was then rinsed withwater, exposed with UV again with an exposure dose of 300 mJ/cm² andpost-baked at 230° C. for 60 minutes, so as to obtain a patternedprotective film.

Application Examples 2 to 8 and Comparative Application Examples 1 to 3

The method for preparing the patterned protective film of each ofApplication Examples 2 to 8 and Comparative Application Examples 1 to 3was similar to that of Application Example 1. The only differenceresides in that the photosensitive resin compositions of Examples 2 to 8and Comparative Example 1 to 3 were used, respectively.

Evaluation Methods 1. Cross-Sectional Shape:

The patterned protective film of each of the Application Examples andComparative Application Examples was subjected to investigation usingScanning electron microscope (SEM), and the cross-sectional shape of thepatterned protective film was evaluated by the following standards:

⊚: Rectangular shape, i.e.,

;

◯: Frustoconical shape, i.e.,

; and

X: Semicircular shape, i.e.,

, or inverted frustoconical shape, i.e.,

.

2. Linear Thermal Expansion Coefficient (α):

The linear thermal expansion coefficient of the protective film of eachof the Application Examples and the Comparative Application Examples wasmeasured at a temperature ranging from 100 to 200° C. using a thermalmechanical analyzer (TMA, manufactured by SEIKO instruments Inc., Model:TMA120C) and was evaluated by the following standards:

⊚: α<200

◯: 200≦α<300

X: α≧300

TABLE 1 Compound (parts by weight, pbw) Solvent Catalyst ReactionReaction (a1) (a2) (a3) (pbw) (pbw) Temperature time MAA HOMS GMA EC-MAAHEMA FA-513M BzMA SM Diglyme PGMEA AMBN ADVN (° C.) (hr) A-1 10 0 65 0 015 0 10 240 0 0 3.0 70 5 A-2 0 40 0 25 5 10 0 20 0 240 0 2.4 70 6 A-3 250 20 20 10 10 15 0 200 40 3.0 0 70 5 MAA Methacrylic acid HOMS2-methacryloyloxyethyl succinate monoester GMA glycidyl methacrylateEC-MAA 3,4-epoxycyclohexylmethyl methacrylate HEMA 2-hydroxyethylmethacrylate FA-513M dicyclopentanyl methacrylate BzMA benzylmethacrylate SM styrene Diglyme diethylene glycol dimethyl ether PGMEApropylene glycol monomethyl ether acetate AMBN2,2′-azobis(2-methylbutyronitrile) ADVN2,2′-azobis(2,4-dimethylvaleronitrile)

TABLE 2 Comparative Examples Examples Components (Parts by weight) 1 2 34 5 6 7 8 1 2 3 Alkali-soluble Resin (A) A-1 100 0 0 100 0 0 100 50 1000 0 A-2 0 100 0 0 100 0 0 50 0 0 100 A-3 0 0 100 0 0 100 0 0 0 100 0O-Naphthoquinonediazidesulfonic B-1 30 0 10 10 50 20 20 10 30 30 0 AcidEster (B) B-2 0 20 0 30 0 0 5 5 0 0 30 Silsesquioxane (C) which has atleast two C-1 10 0 0 15 0 3 10 0 0 0 0 thiol groups in a molecule C-2 05 0 0 5 0 10 0 0 0 0 C-3 0 0 0.5 0 5 0 0 3 0 0 0 Silsesquioxane (C)which has no thiol C-4 0 0 0 0 0 0 0 0 0 0 5 groups in a moleculeSolvent (D) D-1 400 0 100 200 600 400 0 200 300 0 400 D-2 0 200 0 0 2000 400 100 0 300 0 D-3 0 0 0 100 0 0 0 0 0 0 0 Additives (E) E-1 0 0 0.10 0 0 0 0 0 0 0 E-2 0 0 0 0 0.5 0 0 0 0 0 0 E-3 0 10 0 0 0 15 0 0 0 0 0E-4 0 0 0 2 0 0 0 0 0 0 0 Evaluation: Cross-sectional shape ◯ ⊚ ◯ ⊚ ◯ ⊚◯ ◯ X X X Evaluation: Linear thermal expansion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X X Xcoefficient (α) B-1 o-naphthoquinonediazidesulfonic acid ester obtainedby reacting o-naphthoquinonediazide-5-sulfonic acid with1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzeneB-2 o-naphthoquinonediazidesulfonic acid ester obtained by reactingo-naphthoquinonediazide-5-sulfonic acid with2,3,4-trihydroxybenzophenone C-1 COMPOCERAN SQ-101 (commerciallyavailable from Arakawa Chemical Industries, Ltd.) C-2 COMPOCERAM SQ-102(commercially available from Arakawa Chemical Industries, Ltd.) C-3COMPOCERAM SQ105-7 (commercially available from Arakawa ChemicalIndustries, Ltd.) C-4 COMPOCERAM SQ506 (commercially available fromArakawa Chemical Industries, Ltd., no thiol groups) D-1 propylene glycolmonomethyl ether acetate D-2 diethylene glycol dimethyl ether D-3 ethyl3-ethoxypropionate E-1 SH29PA (Dow Corning Toray silicone Co., Ltd.) E-2KBM403 (commercially available from Shietsu Chemical Co., Ltd.) E-3UN-3320HS (commercially available from Negami Industry Co., Ltd.) E-4bisphenol A diglycidyl ether

As shown in Table 2, the photosensitive resin composition of each ofExamples 1 to 8 contains the alkali-soluble resin (A), theo-naphthoquinonediazidesulfonic acid ester (B), the silsesquioxane (C)and the solvent (D), and the resulting patterned protective film of eachof Application Examples 1 to 8 has a good cross-sectional shape and alow linear thermal expansion coefficient.

Moreover, the photosensitive resin compositions of Examples 2, 4, and 6further contain the additives (E), such as urethane (meth)acrylate andbisphenol A diglycidyl ether, and the corresponding patterned protectivefilms have better cross-sectional shapes.

Comparative Examples 1 and 2 do not include the silsesquioxane (C)having at least two thiol groups in a molecule, and Comparative Examples3 includes the silsesquioxane (C) having no thiol group in a molecule.The resulting patterned protective film of each of ComparativeApplication Examples 1 to 3 has an unsatisfactory cross-sectional shapeand a high linear thermal expansion coefficient.

To sum up, the photosensitive resin composition according to thisinvention includes the alkali-soluble resin (A), theo-naphthoquinonediazidesulfonic acid ester (B), the silsesquioxane (C)and the solvent (D), and the corresponding patterned protective filmformed therefrom has a good cross-sectional shape and a low linearthermal expansion coefficient.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. A photosensitive resin composition comprising:(A) an alkali-soluble resin; (B) an o-naphthoquinonediazidesulfonic acidester; (c) a silsesquioxane having at least two thiol groups in amolecule; and (D) a solvent; wherein said silsesquioxane is obtained bysubjecting to condensation a silane material which includes athiol-group-containing silane represented by formula (I):R^(a)Si(OR^(b))₃  (I), wherein R^(a) represents a C₁-C₈ organic groupthat contains a thiol group and that is free from an aromatic group, oran organic group that contains a thiol group and an aromatic group, andR^(b) independently represents hydrogen, a C₁-C₆ alkyl group, a C₁-C₆acyl group, or a C₆-C₁₅ aromatic group.
 2. The photosensitive resincomposition as claimed in claim 1, wherein said alkali-soluble resin (A)is obtained by subjecting a mixture to copolymerization, said mixturecontaining (a1) at least one of an unsaturated carboxylic acid compoundor an unsaturated carboxylic anhydride compound, (a2) an unsaturatedcompound having an epoxy group, and (a3) an unsaturated compounddifferent from said unsaturated carboxylic acid compound, saidunsaturated carboxylic anhydride compound, and said unsaturated compoundhaving an epoxy group.
 3. The photosensitive resin composition asclaimed in claim 1, wherein said o-naphthoquinonediazidesulfonic acidester (B) is in an amount ranging from 10 to 50 parts by weight, saidsilsesquioxane (C) is in an amount ranging from 0.5 to 20 parts byweight, and said solvent (D) is in an amount ranging from 100 to 800parts by weight based on 100 parts by weight of said alkali-solubleresin (A).
 4. The photosensitive resin composition as claimed in claim1, wherein said silane material further includes a crosslinking agentwhich is selected from the group consisting of monoalkoxysilane,dialkoxysilane, trialkoxysilane, tetraalkoxysilane, tetraalkoxytitanium, and tetraalkoxy zirconium.
 5. A protective film formed fromthe photosensitive resin composition as claimed in claim
 1. 6. Anelement comprising the protective film as claimed in claim 5.